C. Koford 2 Proechimys semispinosus January 13, 1957 Barro Colorado Is., Canal Zone. handled + lifted + did not bite. A roati entered lab and killed the rat. Remains showed testis 2.7 x 12 mm. Tail 105, hind foot 52 (sole black). About 50 red chiggers in region anus. Deerm plug at tip penis. 31 January 1957 I on Sunday night of 29 January a ? taken by Bocanegra, without a tail. This I killed this evening; a large ? I trapped one 30ydo. S. of Chapman House in live trap with corn bait. It had torn off right hind foot, thus x1/4. I clipped one stub short. Tail 170 long. Weight 309 1/2 gms. Had fleas, lice, chiggers, + mites; saves a few. Testis about 30 mm. long by palpation. Released, it walked slowly away, tail held about horizontally. I had picked it from cage with bare hand. A sneeze from my wife caused it to struggle much. Later it struggled + scratched when I accidentally struck its nose. Claws sharp. It seemed to tolerated plucking of ecto- parasites from nose, ears, + eyelids. 2 May 1957 Inside Chilobillo Caves, perhaps in dark tunnel, I saw a large one crawled a floor.